Requesting external data — NACC consultants work with investigators to determine whether their requests for external data are feasible and if
so, to create a list of data or specimens available at each Center. Next, NACC consultants will help the investigator
draft a memo for the investigator to send to the Clinical Core Leaders or other appropriate people at the Centers
of interest. All communication to Centers should clearly state that the request is not a NACC initiative and that
Center participation is entirely voluntary. It is also important to note that NACC has a system of creating STUDYIDs
to prevent the linking of NACC IDs to Center-assigned patient IDs, an IRB violation.

NACC routinely provides advice and guidance about the availability and interpretation of data in NACC data sets. A
scientific liaison at NACC is assigned to each project. Through this liaison, investigators can seek advice about
analysis and interpretation as the project proceeds. Data analysis for most projects, however, occurs at the investigator's
home institution. On request, NACC can also provide statistical and methodological consultation.

By mutual consent and subject to staff time constraints, NACC scientists can take on a larger role, including hands-on
data analysis, direct collaboration, and co-authorship. Those arrangements are made on a project-by-project basis
and are normally initiated by the investigator.

For most tests in the UDS Neuropsychological Battery, only the total score is captured. In UDS v2 Initial and Follow-up
Visits, and in a subset of UDS v3 Follow-up Visits, subscale scores were recorded for the Mini-Mental State Examination
(MMSE). In UDS v3 Initial Visits and a subset of Follow-up Visits, item-level data are being collected for the Montreal
Cognitive Assessment (MoCA). For further details, see Form C1 (used in both
UDS v2 and
UDS v3) and Form C2 (used only in
UDS v3 ). See also the
Resarchers Data Dictionary for the UDS.

Many ADCs do retain item-level neuropsychological test results, and access to the item-level data can be sought as
an external data request, as described above (see the first question, on requesting external data, at the top of this
page).

For the neuropsychological test battery used in UDS v1 and UDS v2, a publication by Weintraub and colleagues
[Weintraub 2009] (PDF) provides descriptive information from initial neuropsychological data of more than 3,000
cognitively normal older adults. Linear regression models were developed to estimate the impact of age, sex, and education
on test performance.

The report by Weintraub et al. was not intended as a normative study. However, by combining the initial results of
Weintraub and colleagues with additional statistical information obtained from the study's authors (for example, root
mean square errors for model variables), Shirk et al. have sought to create a useful
regression-based norms calculator
that provides estimated z-scores while taking into consideration the individual's sex, education level, and/or age.
This straightforward tool is available on the web for clinical research use at the NIA Alzheimer's Disease Program
sites. In addition, Shirk et al. aimed to provide an easy and accessible method for calculating norms that other researchers
and clinicians can apply to their own unique, site-specific data sets.

Yes, NACC has CSF data for a small number of UDS subjects. Please see the
Data Element Dictionary for CSF Data to see which values are reported. Apart from CSF data, other biomarkers for
Alzheimer’s and other neurodegenerative diseases are not available at this time. Requests for access to specimens
or external data at the ADCs may be completed as described above (see the first question, on requesting external data,
at the top of this page).